$ant -version
Unable to locate tools.jar. Expected to find it in C:\Program Files\Java\jre6\lib\tools.jar
Apache Ant(TM) version 1.8.2 compiled on December 20 2010
It turns out that I have only installed JRE not JDK.
After install Java JDK and set JAVA_HOME.
$ant -version
Apache Ant(TM) version 1.8.2 compiled on December 20 2010
